Question

A standard rifle has a mass of 3.27 kilograms. If it were used to fire an "elephant gun" round of mass 67.5 grams at +625 meters per second, what would be the recoil velocity of the rifle? Include units in your answer. The answer must be in 3 significant digits.

Answer 1

-12.9 m/s

Explanation:

We have the following information:

`\begin{gathered} m_r=3.27\text{ kg} \\ m_b=67.5\text{ g = 0.0675 kg} \\ V_{\text{fusil}1}=V_{\text{bala}1}=0 \\ V_{\text{bala}1}=625\text{ m/s} \end{gathered}`

We can calculate the recoil velocity that would be the velocity of rifle 2, just like this:

`m_r\cdot V_{\text{fusil}1}+m_b\cdot V_{\text{bala}1}=m_r\cdot V_{\text{fusil}2}+m_b\cdot V_{\text{bala}2}`

Replacing and solving:

`\begin{gathered} 3.27\cdot0+0.0675\cdot0=3.27\cdot V_{\text{fusil}2}+0.0675\cdot625 \\ 0=3.27V_{\text{fusil}2}+42.1875 \\ V_{\text{fusil}2}=-(42.1875)/(3.27) \\ V_{\text{fusil}2}=-12.9 \end{gathered}`

The recoil velocity of the rifle is -12.9 m/s